Chemistry

• Electron arrangement: Shells (2, 8, 8), then sub-shells and orbitals (1s² 2s² 2p⁶…).
• Ionic bonding: Ions, dot-and-cross diagrams, ionic formulae and giant ionic lattices.
• Covalent bonding: Shared pairs, dot-and-cross diagrams, simple molecules and double bonds.
• Metallic bonding: A lattice of positive ions in a sea of delocalised electrons; alloys.
• Structure and properties: Giant covalent, ionic and metallic structures, simple molecules, diamond, graphite, graphene and nanoparticles.
• The mole: Avogadro’s constant, n = m ÷ M and counting particles.
• Gas laws: Pressure, volume and temperature of gases, and absolute zero.
• Atoms and isotopes: Protons, neutrons, electrons, isotopes and models of the atom.